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By Charles H. Bucknam

A gold sampling optimization study was carried out in support of open pit gold mining operations for the Newmont Gold Company Bootstrap-Capstone deposits in Northeastern Nevada. Six bulk samples were tested using fire refining techniques at field particle size, to determine coarse particle heterogeneity of the ores, and by gravity .concentration methods at 10 mesh particle size, to observe any particulate gold liberation. An overall sampling model is presented for the deposit based on the pooled test information, to reconcile the results of coarse particle heterogeneity testing and the fine particle 'liberation testing. The sampling model is used to recommend procedures to control the variability of gold grade estimation due to the fundamental error (nugget effect) during sampling, sample preparation and assaying of the ores and other fundamental variances. The technique of simplified quantitative risk analysis (SQRA) is used to provide an economic justification for implementation of. recommended improvements to field sampling practices.

Jan 1, 1999

By J. Daniel Bryant

Deformation processing of rapidly solidified powder alloys presents a technical challenge different in several ways from the processing of ingot based alloys. The metastable phases formed during planar flow casting of aluminum alloy 8009 (FVS0812) must be safe-guarded from high temperature excursions during processing to avoid decomposition; this restriction prohibits liquid phase sintering of particles during consolidation. The development of strong particle-particle adhesion, therefore, relies on the imposition of very large strains during forming operations to insure sufficient mechanical meshing of the aluminum particles and break-up of prior particle oxide boundaries. These strains are generally much greater than those required for metallurgical transformations in ingot based alloys. In an attempt to quantify the deformation required to improve interparticle bonding, the finite element method (FEM) was employed. Preliminary results which predict the metal flow and strain distribution in several workpiece configurations are discussed. These predictions are then correlated to measurements made on experimental subscale forgings. Lastly, experimentally measured quantities which reflect the degree of interparticle bondingg are related back to FEM model predictions.

Jan 1, 1992

By Tailoka F.

Various metallurgical residues from iron and steel making processes have been treated by chlorination in excess air with hydrogen chloride gas generated from the combustion of scrap polyvinyl chloride (PVC). The residues include dust from both the electric arc and blast &maces, hydrocyclone overflow, zinc - lead blast furnace slags and dust rich in zinc and copper from copper refining. Chlorination is achieved either directly by mixing the residues with scrap PVC or indirectly in a two furnace system. In the latter, scrap PVC is combusted between 523 and 573 K in a horizontal furnace and the resulting gases are then reacted with metallurgical residues in a vertical furnace at 1166 to 1329 K. Gas chromatography, thermogravimetric measurements, XRD and AAS have been utilised to study the reactions. The recovery of non ferrous metals is as high as 80 to 90 % and only a negligible amount of iron is carried over. The optimum temperature for combustion is between 518 and 573 K. Above 600 K, the evolution of HCI is so fast that sufficient chlorination is not achieved. Analysis showed that no dioxins were present in the gases, the residues or the chlorides.

Jan 1, 1997

By Stephanie Trant

Montana Tech has been engaged in fundamental research on the processing of critical materials for more than a decade. Efforts include examining novel reagents for the flotation of Rare Earth Minerals (REMs). For this paper, research results on a collector, salicyl hydroxamic acid (SHA), are presented. Various REMs were examined and include the rare earth oxides (REOs), carbonates (RECs), and phosphates (REPs) of a suite of Rare Earth Elements (REEs). Differences are attributed to solution and surface chemistry, coordination number, and ionic diameter. SHA adsorption follows an ion-exchange process that leads to chemisorbed and surface-precipitated states, depending mostly on pH. Many effects are directly attributed to lanthanide contraction. Results should also be applicable to other REM/collector systems and further suggest that REM flotation should consider dual collectors.

By D. M. Dabbs

A static dew point technique has been used to evaluate the solubility of arsenic in ?slag and its dependency on P02 at temperatures of 1458 and 1523K. The ferrous-ferric ion ratio of the slags ranged from 3.9 to 23.8. These values correspond to partial pressures of 02 ranging from 10-8 to 10-12 atm. The solubility of arsenic in slag was found to be independent of? P02? The data indicate that elemental arsenic exists in silicate ?slags. This result was further substantiated by mass .spectrometric analysis of doped slag specimens.

Jan 1, 1983

By Reza Kamali, Mohsen Bashiri, Hadi Fanisalek

"Half of the input energy to aluminum reduction cell will be lost as waste heat which could be studied for possible recovery. Since price of energy is increasing and the main production cost in primary aluminum industry is energy, so waste heat recovery consideration will be interesting. One of the possible choices for recovering is from aluminum exhaust gases that needs minimum modifications for reduction cell and has no influence on cell heat balance which is vital for the operation. By using heat exchangers with in-line and staggered tube arrangements which placed before fume treatment plant (FTP) we will be able to recover enough amount of heat. The main challenging problem which is necessary to overcome will be the heat exchanger material and its design because of corrosive and dusty exhaust gases from potroom. In this paper, a desalination system with six effects of evaporator is proposed for producing distilled water by using recovered heat from hot exhaust gases. The calculated amount of produced distilled water is around 27,000 / in this specific suggested desalination plant. The suggested desalination plant is based on Hormozgan Aluminum Company data (Hormozal) in Bandar Abbas, Iran which is constructed by the Persian Gulf.IntroductionWaste heat losses arise both from equipment inefficiencies and from thermodynamic limitations on processes. The exact quantity of industrial waste heat is poorly quantified, but various studies have estimated that as much as 20 to 50% of industrial energy consumption is ultimately discharged as waste heat [1]. In order to achieve a final decision for establishing the waste heat recovery plant in any type of industry, a strong feasibility study is mandatory. Also, we need to remember that the possible amounts of energy and suggested process plant for recovery have to be investigated before starting any feasibility study. This kind of study which is important to be finished before moving to feasibility step is mainly a theoretical study, and was done for the Hormozgan Aluminum Company (Hormozal). In addition to the exhaust gases from the potroom, the exhaust gases from anode baking plant appear to have a better potential for waste heat recovery compared to potroom exhaust gases. The average temperature of exhaust gases from anode baking kiln is 120°C higher than the exhaust gases temperature in the potroom. This needs further investigation in a different study, because this study is just focusing on potroom exhaust gases."

Jan 1, 2011

By Omid Marzoughi

Chromium has a wide range of applications, including as an alloy addition in various steels and also as a corrosion resistance coating. Carbothermal reduction of chromite ore (FeCr2O4) in a submerged arc furnace is an important industrial process for extracting chromium, but the energy consumption is excessive. It is suggested that one area for future research is the low temperature carbothermic solid state reduction of chromite to produce an intermediate product, which can subsequently be upgraded to ferrochromium. In this regard, a thermodynamic model has been developed to investigate this process and the effects of temperature, carbon additions and ore composition on the recovery of chromium and the grade of the ferrochromium, have been studied. Further development of the model may allow it to be applied to the simulation of other processes for the recovery of chromium from chromite ores.

By Shadia J. Ikhmayies

"Tin oxide (SnU2) thin films of thicknesses in the range 100-600 nm were prepared on glass substrates by vacuum evaporation at ambient temperature. The films were characterized by transmittance measurements, X-ray diffraction (XRD), scanning electron microscope (SEM) observations and energy dispersion X-ray analysis (EDAX). It is found that the films have high transmittance and non sharp absorption edges. XRD diffractograms showed that the films are amorphous and the SEM micrographs showed that the surfaces are smooth, uniform and well covered with the material. The EDAX analysis showed that the films are deficient in oxygen. Indirect optical bandgap energy and Urbach tailing in the bandgap was observed, and the width of the tail, which is related with disorder and localized states, was estimated.IntroductionTin oxide is an n-type wide bandgap semiconducting material with a direct bandgap energy of 4 eV and an indirect bandgap of 2.6 eV [1], where inherent oxygen vacancies act as an n-type dopant [2], Tin oxide thin films have been used for transparent electrodes in photoelectric conversion devices namely amorphous silicon solar cells, liquid crystal displays, gas discharge displays, etc. [3]. Perfectly amorphous thin SnO2 films show good electrical response to reducing gases in air and could, hence, be applied to construct semiconductor gas sensors where the metal oxide films function as a monograin-eqivalent active layer [4]. Amorphous SnU2 can also be used in extended gate field-effect transistors (EGFET) as a pH sensor, where the sensitive part is made of the SnO2/Al structure. This device can be used to detect and to quantify any kind of substance that can produce or consume protons, like an enzymatic reaction, therefore showing a large range of applications as biosensors [5].There are different methods to prepare SnO2 films, such as atomic layer deposition (ALD) [6], reactive magnetron sputtering [7], chemical vapor deposition [8, 9], dip coating [10], spray pyrolysis (SP) [3, 11-14], and evaporation [8], The thermal evaporation method was chosen to produce SnO2 thin films in this work because deposition by this technique does not present any compositional problems. In addition, it is a low temperature technique, which increases the probability of producing amorphous films. To increase this probability, the films were deposited at ambient temperature."

Jan 1, 2012

By Marco V. Ginatta

Current world production, 60'000 ton/y, is exceedingly too small for titanium's extraordinary combination of favorable properties; it should be 1,000,000 ton/y (7% of stainless-steel). Prices that competitively sustain that sales volume are achievable only with electrolytic production, as it is for all other commercial nonferrous metals. But titanium does not have its commercial electrolytic plants yet, because of producers decisions and strategies, scientists works, industrial problems with chloride process, lack of consumers sponsors. Fluoride high temperature process has the advantages of aluminum electrolysis, plus other favorable characteristics specific to titanium and its feed material. One electrolytic titanium potroom replaces several different plants used for sponge production. Production of titanium ingots with zero defect is achieved. The solidified cathode rectangular slabs are suitable for direct rolling.

Jan 1, 2001

By Christoph Zschiesche

Managing complex material streams within a lead smelting/reduction process has a long history at Aurubis. After modernization of the secondary lead smelter in 1991, Aurubis operates an electric furnace and a Peirce Smith converter to process complex secondary materials. This process links the copper and the lead metallurgy allowing Aurubis to properly combine primary and secondary process lines to optimize the processing of complex raw materials and smelter intermediates. However, combination of copper and lead metallurgy processing requires a continuous evaluation as raw material quality and composition varies. This paper describes Aurubis lead smelter processing and provides some fundamental considerations to optimize the lead processing, in particular with aspects related to speiss formation

By Allan MacRae

Freeport-McMoRan Inc. operates an ISASMELTTM furnace for the smelting of copper concentrate at the Miami Smelter in Claypool, Arizona. In May 2017, the furnace was restarted after incorporating newly designed copper cooling elements from just above the tap hole to the underside of the roof. The objective of the improved cooling design was to extend campaign life by eliminating existing failure mechanisms with the wall refractory. In addition to upgraded bathline coolers and complete coverage of the gas offtake transition, or ‘kettle’, with plate coolers, a novel arrangement of coolers was installed in the remaining freeboard area. The shell required significant cutting and re-stiffening, as well as extensive modification of the cooling water piping. Based on performance observed to date, it is expected that smelter throughput will be increased due to extended ISASMELTTM refractory campaign life.

By Yoshinobu Fukumori, Testuya Watanabe, Futoshi Shikata, Hiroyuki Tokumitsu, Hideki Ichikawa, Masahito Miyamoto

Nano-particulate systems have attracted much attention recently in pharmaceutical field as drug carriers and functional components of pharmaceutical dosage forms. This paper describes our approaches in design and preparation of nano-particulate systems, including lipid nano-emulsions, chitosan nanoparticles and thermosensitive acrylic nanoparticles, for certain pharmaceutical applications mentioned below. The lipid nano-emulsions with their particle size smaller than 100 nm were prepared for gadolinium neutron-capture therapy (Gd-NCT) of cancer by a thin-film hydration method with sonication, and intraperitoneally injected into Greene's melanoma (melanotic No. 179)-bearing Syrian hamsters. This provided such a high gadolinium concentraton in tumor as 107 µg/g tumor (wet basis) at 48 h after administration. As an alternative gadolinium nano-carrier for Gd-NCT, biodegradable and highly gadopentetate-loaded chitosan nanoparticles (Gd-nanoCPs, 426 mTI in particle diameter and 9.3% in Gd content) were prepared by a novel emulsion-droplet coalescence technique. A significant tumor-killing effect could be obtained when Gd-nanoCP suspension was injected intratumorally twice 24 and 8 hours before neutron irradiation into B 16Fl O melanoma-bearing mice and subsequently thermalneutron was irradiated toward tumor site with a flux of 2 x 109 n/cm2/sec for 60 min. As one another application of nanoparticles, a novel acrylic composite latex with a hydrophobic core and a thermosenstively swellable shell was designed for fabricating microcapsules showing thermosensitive mode of drug release. The microcapsules with the composite latex-dispersing membranes exhibited an exceptionally rapid on-off response of drug-release in a thermosensitive manner.

Jan 1, 2000

By A. Dadgar

The adsorption kinetics of AuBr4 on Dowex ® -21K ion-exchange resin were studied and found to be independent of the initial gold, bromine, and base metals concentrations. A commercially-available undivided hypochlorite generating cell was used to generate bromine from simulated mixed halide (Br-/CI-) solutions. Electrolyses were performed with solutions containing very low Br' ion concentrations. The current efficiencies were 80-90%, and Br- ion utilization was maximized. A detailed economic assessment was made considering the capital and the operating costs for a 1000 mtpd gold ore processing plant. The toxicity and discharge levels of bromide, bromine, and cyanide were compared from a detailed analysis of the published literature data. Comparing bromine vapor with hydrogen cyanide gas for a given length of exposure, the lethal concentration of bromine is about 3 times less than hydrogen cyanide. The toxicity of sodium bromide is similar to that of sodium chloride. Acute poisoning to bromides and chlorides is rare because of their low toxicities. The allowed discharge levels of Br-, Br2, and CN- in fresh water are 250, 0.1, and 0.005 mg dm-3, respectively.

Jan 1, 1992

By Huimin Lu, Zegao Sun, Zhijiang Gao

The traditional Ti6Al4V alloys were obtained by the smelting reduction of V-Ti bearing beach placer by rotary hearth furnace and aluminothermic reaction in laboratory. First, it gets he lp from combined rotary hearth furnace and grinding magnetic separation process to prepare titanium slag containing vanadium. In this study, a neural network model was used. The comparisons between experiment results and neural network simulation results show that genetic algorithm (GA)-based on back propagation (BP) method can predict the degree of reduction and separation of iron and slag with higher prediction accuracy. Then by aluminothermic reaction process, the optimized process parameters for Ti-V-Al alloys were searched. Al can deoxidize metal V and Ti from the metal oxides of artificial rutile containing vanadium. Finally, traditional Ti6Al4V alloy can be obtained by remelt and adjust the constituents.

Jan 1, 2016

By O. Norman Lotter

There are many scales of innovation in the pursuit of concentrator performance improvement, including paradigm change, inventive change and incremental change. All are important, but the last is low risk, low cost and has a relatively high probability of success, given the right metallurgical skills. Seeking continuous improvement is also essential to ensure that performance does not decline over time due to ore type changes, personnel changes, equipment wear and other factors. When properly implemented, these small gains offer a very high rate of return for the project cost because they are made from marginal, not total, operating costs of the plant. To be effective this approach requires plant trials that use designed structure and appropriate statistics to test the observed differences arising from the old and new process treatments, be they a change in flotation reagent, in grind, pulp density, etc. However the pursuit of small but financially significant performance gains is often regarded as fruitless because of the range of variance in plant data, and the consequent difficulty of ‘proving’ that a benefit has been achieved. Opportunity for improvement is thus sometimes relegated to the realm of the impossible, or at best, treated with skepticism. Operations managers prefer to look for the larger gains, which are easier to demonstrate and prove. Unfortunately, these are seldom to be found; rather, a large gain can be more easily made by executing a series of small recovery improvements that are together equivalent to the ephemeral single large gain. In this paper we advocate a policy of continuing improvement driven by rigorous performance testing protocols and a formal ‘risk analysis’ approach to judging the efficacy of changes implemented in the plant. Following these simple procedures allows rational decisions to be made on the basis of quantifying risk and reward. In particular we consider the choice of hurdle rate for decision-making which best balances risk and reward. It is shown through case studies from actual industrial practice that this approach is practical and delivers significant financial value to the operation.

By G. Nazari

ERAMET, through its subsidiary COMILOG, have rights to a rich niobium and rare earth deposit inGabon. The Mabounié deposit, is located 50 kmfromthe town of Lambaréné, in a fairly remote location. ERAMET has been developing a process to recover value metals for several years, and approached Hatch Ltd. to design a sizeable Demonstration Plant to help them further optimize the process, and prove the flowsheet is technically viable. The process employs concentration techniques to recover an upgraded Nb/REE feed material for processing in the subsequent leach step. Rare earths and niobium are selectively leached, and subsequently precipitated. Following precipitation, rare earths undergo bulk separation and are purified to produce LRE and mixed MRE/HRE products, which will be further processed by Third Parties. This paper provides a high-level overview of the process, summarizes the motivation for a Demonstration Plant in the vicinity of the deposit, and discusses technical challenges faced during the flowsheet definition and design phase. Key challenges are focused on and summaries of the methodologies used to address each challenge, as well as the solutions to overcome the challenges, are discussed. The paper provides motivation for further process simplification and concludes with a project update.

By Vasil Kopaleishvili

The bainitic Fe-C-Si alloys with optimum content of retained austenite serve as ?containers? for storing of hydrogen. Both the vacancies of fcc lattice and the possibility of forming hydrides of silicon and other alloying elements will be used. The idea is based on our scientific hypothesis. There is the silicon threshold (Si=0,50%) in "Fe-Si" system and Fe-C bainitic alloys, above which it causes self-organized phenomena: sudden increase of hydrogen solubility and amount of retained austenite in the alloy after ??ß transformation, formation of two supersaturated solid solutions <a??r>, "rejuvenation? and its reverse process. Rapprochement of iron atoms when Si=0,50%, causes appearance of new covalent forces where uncompensated electrons of 3d-subshell are involved and it provokes synergetic phenomena. They ?free? silicon atoms from the previous bonds. After that silicon itself becomes a getter of hydrogen using vacancies (14) of 3P2(6)d0(10) subshell and it results in sudden increase of hydrogen solubility in metal. Simultaneously sudden decrease of iron activity takes place. That in its turn ?releases? the carbon. Thus, its redistribution, controlling the bainitic transformation, is hastened. It stipulates for creation of ?brittle bainite" B[a(C,H)+?r(C,H)] after ??ß transformation. While weathering of metal, "rejuvenating", hydrogen diffuses in ?islets? of retained austenite and ?relaxed bainite? (B[(C)+?r(C,H+H)]) is obtained. When heating austenite ?(C,H) is obtained, and after cooling ?brittle bainite? is obtained, etc. Presented scientific hypothesis explains the available experimental facts ("rejuvenation? and its reverse process, graphitization, weldability, forming of flakes, reaching high strength, etc.) in a new manner, as well as, gives real opportunity for creating of new trends in many fields, e.g. iron based HAA. Provisional data having been obtained are encouraging.

Jan 1, 2006

By Rajashekhar Marthi

Lithium is a key component for future electric vehicle batteries and energy storage. The future availability of lithium to meet the growing demands remains in question. Around 60% of lithium resources exist in the form of continental brines. Traditional methods to recover lithium from brines use solar concentration with precipitation and have found limitations in lithium extraction due to interference of Mg in high Mg/Li brines. Thus, there is a need for highly selective adsorbents. Recently, spinel structured delithiated lithium manganese oxides have demonstrated promising results. However, due to the small particle sizes, it is economically difficult to recover the adsorbents and thereby limits industrial applications. In our work, LiMn2O4 ion sieve was synthesized and immobilized on diatomaceous earth. Fundamental adsorption studies were carried out in lithium buffer solutions to understand the nature of adsorption and kinetics. The adsorbents were also tested for recycle stability, as well as recovery of lithium from Great Salt Lake water samples.

By Robert P. Stevens

It is important for a refractory supplier to make systematic petro-graphic examinations of products which have been in service in the furnaces and kilns of customers. The petrographic examination of refractory service samples involves the microscopic study of polished and/or thin sections, supplemented by electron probe microanalysis, as well as the bulk chemical and XRD analysis of zones in the samples. The evolution of the A. P. Green Refractories Company petrographic laboratory is described, and the application of petrographic methods is illustrated in the examination of service refractories from a Portland cement rotary kiln and an AOD stainless steel vessel. The objectives of such studies are to assist the customer in the solution of his refractory problems, and to accumulate data which are of use in the design of improved refractory products.

Jan 1, 1981

By Amy Anderson

The Silica (SME) Technology has been utilized on three separate projects focusing upon the stabilization of mercury-contaminated materials: at the Mother Lode Mine in Oregon, the Sulfur Bank Mercury Mine in California and at a former chloralkali plant in British Columbia. Each of the projects relied primarily on the results collected via EPA Method 1311 TCLP, with additional tests such as SPLP, humidity cell tests and other supporting tests employed as well. Both technical and economic performance of the silica-based technology was evaluated as well as that of competing technologies in some cases. Results established that in each of the three projects an SME chemical dosage rate of 3% chemical by weight of soil/sludge was the optimal ratio required to achieve project treatment objectives, TCLP test results exhibited a reduction in the leachable mercury from the treated materials ranging between 75% and 99% as compared to untreated material, satisfying the technical objectives for each project, Project costs ranged from $l5.00 - $18.26 per metric ton.

Jan 1, 2003